I can't believe how many people don't seem to realise that putting very hot or wet things, like wet dishcloths, mugs of tea, cold drinks etc on wooden tables or furniture stains them forever! My husband does it, other family members do it, the cleaner does it! Our dining table has rings from drinks on it, so does our coffee table, and now so does a dressing table in the bedroom. I have explained to them repeatedly you need a coaster under drinks. Obviously children aren't aware of this but surely adults should be?
IANBU to expect adults to proactively protect nice wooden surfaces from hot wet things
AIBU yes, it's trivial and life is too short, I should just tolerate it